JP6198029B2 - Waste water treatment system and waste water treatment method - Google Patents

Description

  The present invention relates to a wastewater treatment system having an ozone treatment device and a wastewater treatment method.

  When wastewater such as industrial wastewater, domestic wastewater, and sewage is discharged into a river or sea area, the biochemical oxygen demand (Biochemical Oxygen Demand, BOD), chemical oxygen demand (Chemical Oxygen Demand, Substances that cause pollution must be removed from the wastewater by the wastewater treatment system so that the COD) and suspended solids (SS) are below the specified wastewater standards. Conventionally, as a wastewater treatment system that removes substances that cause pollution from wastewater, physicochemical treatment such as coagulation sedimentation treatment and ion exchange treatment, and biological treatment such as aerobic treatment using activated sludge and biofilm are adopted. It has been known.

  For example, Patent Document 1 describes a wastewater treatment system including a biological treatment tank that performs biological treatment with aerobic microorganisms and a precipitation tank that separates wastewater after biological treatment into a precipitate and a supernatant. . In the biological treatment tank of this wastewater treatment system, the wastewater is mixed with activated sludge and aeration air to be aerobically biologically treated. In the sedimentation tank, the biologically treated waste water and activated sludge flow from the biological treatment tank, the activated sludge is settled and separated, and the supernatant liquid is discharged as treated water.

JP 2005-131594 A

  However, in the wastewater treatment system that employs the conventional biological treatment, there is a problem that a large amount of excess sludge such as contaminated solid waste and activated sludge is generated, and the cost of discarding the generated waste is high. It was.

  The present invention has been made to solve such a problem, and a wastewater treatment system and a wastewater treatment method capable of suppressing the generation of waste such as excess sludge and reducing the waste disposal cost. The purpose is to provide.

  The wastewater treatment system according to the present invention is stored in a wastewater storage tank that stores wastewater containing organic matter, an ozone treatment device that reduces the organic matter contained in the wastewater by ozone treatment, and the wastewater storage tank. The aerobic microorganisms are brought into contact with the drainage recirculation mechanism that feeds the wastewater to the ozone treatment device and circulates the ozone-treated wastewater to the wastewater storage tank, and the wastewater that contains the ozone-treated wastewater and is sent from the wastewater storage tank. And a biological treatment tank that reduces organic matter contained in the waste water.

  In the wastewater treatment system according to the present invention, the drainage recirculation mechanism is provided between the wastewater storage tank and the ozone treatment apparatus, and is supplied with ozone treatment for feeding the wastewater stored in the wastewater storage tank to the ozone treatment apparatus. An ozone treatment recirculation pipe provided between the water pipe, the waste water storage tank and the ozone treatment device for circulating the ozone treated waste water to the waste water storage tank, and the waste water stored in the waste water storage tank to the ozone treatment device. It is preferable to provide an ozone treatment water pump for feeding water.

  Moreover, in the wastewater treatment system according to the present invention, provided between the wastewater storage tank and the biological treatment tank, the suspended matter or solid matter contained in the wastewater is separated, and the wastewater from which the suspended matter or solid matter is separated, It is preferable to further have a separation device for feeding water from the waste water storage tank to the biological treatment tank.

  In the wastewater treatment system according to the present invention, it is preferable that the wastewater treatment system further includes a floss circulation pipe for circulating the suspended matter separated in the separation device to the wastewater storage tank.

  Moreover, in the wastewater treatment system according to the present invention, the separation device is preferably a pressurized flotation device or a coagulation sedimentation device.

  Further, in the wastewater treatment system according to the present invention, the ozone treatment device includes a nozzle for ejecting ozone gas, and a swirling jet that stirs ozone gas and drainage by generating a swirling phenomenon of the jet by the ozone gas ejected from the nozzle. It is preferable that it is a type | formula ozone treatment apparatus.

  In the wastewater treatment system according to the present invention, the ozone treatment device is preferably an ejector-type ozone mixing device or an ozone diffuser.

  In the wastewater treatment system according to the present invention, the drainage storage tank includes a measuring instrument that measures the amount of organic matter in the wastewater stored in the wastewater storage tank, and the amount of organic matter in the wastewater stored in the wastewater storage tank is equal to or greater than a predetermined threshold value. If the amount of organic matter in the waste water is less than a predetermined threshold, the control device for sending the waste water stored in the waste water storage tank to the biological treatment tank. It is preferable to have.

  Moreover, in the wastewater treatment system according to the present invention, the wastewater treatment system further includes a sedimentation tank that separates the wastewater into a precipitate and a supernatant, and the sedimentation tank recirculates the sediment that has settled in the sedimentation tank to the wastewater storage tank. It is preferable to provide.

  The wastewater treatment method according to the present invention includes a step of storing wastewater containing organic matter in a wastewater storage tank, a step of causing the drainage recirculation mechanism to send the wastewater stored in the wastewater storage tank to the ozone treatment device, and an ozone treatment device. , The step of reducing the molecular weight of organic matter contained in the wastewater by ozone treatment of the discharged wastewater, the step of circulating the wastewater recirculation mechanism to the wastewater storage tank, the biological treatment tank A step of bringing aerobic microorganisms into contact with the wastewater containing the treated wastewater and fed from the wastewater storage tank to reduce organic matter contained in the wastewater.

  The wastewater treatment system and the wastewater treatment method according to the present invention can suppress the generation of waste such as excess sludge and reduce the waste disposal cost. In addition, the wastewater treatment system and the wastewater treatment method according to the present invention can improve the purification effect of biological treatment, and can sufficiently remove substances that cause pollution from wastewater.

It is a schematic diagram for demonstrating the outline | summary of the waste water treatment system. It is a schematic diagram for demonstrating an example of the waste water treatment by the waste water storage tank 2 and the ozone treatment apparatus 3. FIG. It is a schematic diagram for demonstrating an example of the waste water treatment by the biological treatment tank. It is a schematic diagram for demonstrating an example of the waste_water | drain process by the sedimentation tank. 3 is a flowchart illustrating an example of wastewater treatment by the wastewater treatment system 1. 1 is a schematic diagram for explaining an outline of a wastewater treatment system 10. FIG. It is a schematic diagram for demonstrating an example of the waste_water | drain process by the separation apparatus. 1 is a schematic diagram for explaining an outline of a wastewater treatment system 100. FIG. 3 is a flowchart illustrating an example of wastewater treatment by the wastewater treatment system 100.

  Hereinafter, various embodiments of the present invention will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, and extends to the invention described in the claims and equivalents thereof.

(First embodiment)
Drawing 1 is a mimetic diagram for explaining an outline of waste water treatment system 1 of a 1st embodiment. The wastewater treatment system 1 of the first embodiment has a function of removing substances that cause pollution from wastewater discharged from wastewater generation sources such as factories or homes, and includes at least a wastewater storage tank 2 and an ozone treatment device 3. The biological treatment tank 4 and the sedimentation tank 5 are provided. The substance causing the contamination is, for example, an organic substance. Hereinafter, the organic substance may be simply referred to as an organic substance.

  The waste water storage tank 2 is, for example, a flow rate adjusting tank, stores the waste water flowing in from the waste water generation source, and has a function of sending water to the ozone treatment apparatus 3 and the biological treatment tank 4 for performing post-treatment, and the ozone treatment apparatus 3. It has a function to store the drained water circulated from In addition, the waste_water | drain which flows in from a waste_water | drain generation source may be stored in a raw | natural water tank (not shown) first, and may be made to send water to the waste water storage tank 2 next.

  The drainage storage tank 2 includes an ozone treatment water pump 21 and a biological treatment water pump 22. The ozone treatment water pump 21 feeds the waste water stored in the waste water storage tank 2 to the ozone treatment device 3. The biological treatment water pump 22 feeds the wastewater stored in the wastewater storage tank 2 to the biological treatment tank 4 when a predetermined time has elapsed since the wastewater stored in the wastewater storage tank 2 was supplied to the ozone treatment device 3. To do.

  The ozone treatment device 3 mixes the wastewater sent from the wastewater storage tank 2 with ozone gas, performs ozone treatment, and circulates the wastewater after ozone treatment to the wastewater storage tank 2. The ozone treatment device 3 blows out ozone gas into the wastewater sent into the ozone treatment device 3, thereby causing organic substances contained in the wastewater to react with the ozone gas and decompose. In particular, the low-degradability polymer contained in the wastewater is reduced in molecular weight by reacting with ozone gas, which increases the amount of aerobic microorganisms that can be adsorbed to pollutants in the subsequent biological treatment, and the pollutant removal efficiency. Will increase. Moreover, since the amount of dissolved oxygen in the waste water increases due to the reaction between the organic matter and the ozone gas, the function of the activated sludge in the subsequent biological treatment can be improved. The ozone treatment device 3 performs a so-called swirling jet ozone treatment using, for example, a stirring device described in Japanese Patent No. 4195782. Hereinafter, a device that performs a swirling jet ozone treatment may be referred to as a swirling jet ozone processing device. A known ozone mixer or the like may be used as the ozone treatment device 3. The ozone treatment device 3 is not limited to the swirling jet type ozone treatment device and the ozone mixer described above, and any device may be used as long as the waste water and ozone are mixed.

  The biological treatment tank 4 biologically treats the wastewater sent from the wastewater storage tank 2 with activated sludge. The activated sludge is a mud aggregate of aerobic microorganisms that oxidatively decompose organic substances contained in wastewater, and the aerobic microorganisms are bacteria, protozoa, metazoan bacteria, and the like. In the biological treatment tank 4, aerobic microorganisms are fed from the wastewater storage tank 2 and adsorbed to pollutants in the wastewater containing organic matter, and by consuming oxygen, the organic matter is oxidatively decomposed or absorbed and separated. Purify wastewater. The waste water purified by the biological treatment tank 4 flows into the sedimentation tank 5. Moreover, in the biological treatment tank 4, the wastewater sent from the wastewater storage tank 2 may be biologically treated by a biofilm method. In the biofilm method, a biofilm filter medium to which aerobic microorganisms are attached is placed in the biological treatment tank 4, and the aerobic microorganisms attached to the biofilm filter medium come into contact with pollutants including organic matter in the waste water. The organic matter is oxidatively decomposed or absorbed and separated, and the waste water containing the organic matter is purified. The biological treatment in the biological treatment tank 4 is not limited to the activated sludge method and the biofilm method described above, but may be a method of contacting aerobic microorganisms with organic matter in the wastewater, such as a sprinkling filter bed method and a rotating plate contact method. Any method may be used.

  In the settling tank 5, the wastewater flowing from the biological treatment tank 4 is settled and separated into a precipitate and a supernatant liquid. Precipitates are activated sludge and pollutants in the waste water flowing from the biological treatment tank 4 and settle due to the difference in specific gravity with water. Then, after a predetermined time has passed since the wastewater was introduced from the biological treatment tank 4, the supernatant liquid separated and settled was treated as wastewater from the precipitation tank 5, a sewage treatment facility such as an industrial park, a community plant such as an apartment house, a sewer , Discharged into rivers or sea areas.

  As described above, since the wastewater treatment system 1 can reduce the organic molecules contained in the wastewater by the ozone treatment device 3 before biologically treating the wastewater flowing in from the wastewater generation source in the biological treatment tank 4, purification of biological treatment The effect can be improved. Therefore, the wastewater treatment system 1 can sufficiently remove substances that cause sludge from the wastewater. Moreover, since the wastewater treatment system 1 can reduce the amount of sludge discarded, the amount of industrial waste treated can be reduced, and the waste disposal cost can be reduced.

  FIG. 2 is a schematic diagram for explaining an example of waste water treatment by the waste water storage tank 2 and the ozone treatment device 3.

  The drainage storage tank 2 stores the wastewater flowing in from the drainage source through the storage tank inflow pipe 60 in the drainage storage tank 2. The ozone treatment water pump 21 feeds the waste water stored in the waste water storage tank 2 to the ozone treatment device 3 through the ozone treatment water supply pipe 61.

  The ozone treatment device 3 performs ozone treatment by mixing waste water sent from the waste water storage tank 2 with ozone gas. First, ozone gas supplied into the ozone treatment device 3 is generated by an ozone generator (not shown). The ozone generator, for example, compresses air with an air compressor, generates concentrated oxygen gas from the compressed air by a PSA (Pressure Swing Adsorption) method, and further applies high voltage using a discharge unit or the like from the concentrated oxygen gas. Ozone gas is generated.

  As shown in FIG. 2, the ozone treatment device 3 includes a cylindrical container 31 that stores wastewater to be treated, and an ozone gas ejection nozzle 32 that is disposed so as to protrude upward from the bottom surface of the cylindrical container 31. . The inner diameter of the cylindrical container 31 is D, and the depth from the drainage liquid surface to the tip of the ozone ejection port 33 of the ozone ejection nozzle 32 is H1. The waste water stored in the waste water storage tank 2 is appropriately supplied through the ozone treatment water supply pipe 61 so that the height of the liquid level in the cylindrical container 31 is kept constant.

  As described in Japanese Patent No. 4195782, the ratio (H1 / D) of the depth H1 of the ozone outlet 33 to the inner diameter D of the cylindrical container 31 is in the range of about 0.3 to about 1.0. When the gas satisfying a certain flow rate is ejected from the ozone ejection port 33, the waste water in the cylindrical container 31 is swung in the direction of the arrow A as shown in FIG. Here, the certain condition is that the flow rate Q of the gas to be ejected is equal to or higher than the flow rate satisfying ρQ2 / (σD3) = 10−5 and equal to or lower than the flow rate at which bubbles do not blow through the liquid surface. Where ρ is the density of drainage and σ is the surface tension of the drainage. And if the waste_water | drain above the ozone jet nozzle 33 turns in the arrow A direction, the waste water below the ozone jet nozzle 33 will rotate in the arrow B direction of a reverse direction by the angular momentum conservation law.

  Thus, in the ozone processing apparatus 3, the swirling phenomenon of a jet flow arises by ejecting ozone gas. Accordingly, in the ozone treatment apparatus 3, the waste water in the cylindrical container 31 is agitated without using a mechanical drive source such as a propeller. The ozone treatment device 3 is thus more efficient than the method of simply injecting ozone gas from the bottom surface of the cylindrical container 31 by stirring the waste water in the cylindrical container 31 and dispersing the ozone gas as fine bubbles in the waste water. It reacts with ozone and waste water. Then, due to the strong oxidizing power of ozone, high molecular organic substances such as oil in the wastewater are reduced in molecular weight. Note that the ejection and ejection time of ozone gas from the ozone generator are controlled by an ozone control unit (not shown) so that the amount of organic matter in the wastewater is equal to or less than a predetermined threshold. The amount of organic substances is TOC (Total Organic Carbon) and COD.

  Thus, according to the swirling jet type ozone treatment in which the ozone gas is ejected to generate a swirling jet and the ozone gas and the waste water react with each other, the amount of aerobic microorganisms that can be adsorbed to the pollutant in the biological treatment in the subsequent stage is large. Thus, it becomes possible to increase the removal efficiency of pollutants.

  In addition, the swirling jet type ozone treatment has various advantages such as low sludge generation and excellent deodorizing and decoloring effects in addition to the effect of reducing the molecular weight of high molecular organic substances such as oil. .

  In the wastewater treatment system 1, the swirl jet ozone treatment has been described as a treatment for reacting ozone gas and wastewater. However, the ozone gas is dissolved in the wastewater by an ejector-type ozone mixing device or an ozone diffuser. May be. For example, an ejector-type ozone mixing device inhales ozone gas using the vacuum action caused by the negative pressure generated when the wastewater is ejected as a contracted flow, and ejects ozone gas as bubbles into the wastewater, thereby generating ozone gas and wastewater. Is a device for mixing.

  As shown in FIG. 2, the drainage storage tank 2 and the ozone treatment device 3 are connected via an overflow pipe 62. That is, when the water level of drainage in the ozone treatment apparatus 3 (in the cylindrical container 31) rises to the height (H2) or more of the lower end position of the connection port of the overflow pipe 62 in the cylindrical container 31, it is equal to or higher than the connection position. The waste water flows back to the waste water storage tank 2. Therefore, the ozone treatment water pump 21 feeds the waste water in the waste water storage tank 2 through the ozone treatment water supply pipe 61 to the ozone treatment device 3, and the ozone treatment device 3 performs ozone treatment on the sent waste water. The wastewater after the ozone treatment flows back to the wastewater storage tank 2 through the overflow pipe 62, the wastewater in the wastewater storage tank 2 and the wastewater after the ozone treatment are mixed, and the mixed wastewater in the wastewater storage tank 2 is treated with ozone. Water is sent to the device 3.

  Thus, the ozone treatment water pump 21, the ozone treatment water supply pipe 61, and the overflow pipe 62 circulate the drainage of the drainage storage tank 2 and the wastewater of the ozone treatment device 3. Then, after the drainage circulates for a predetermined time, the wastewater in the drainage storage tank 2 is fed by the biological treatment water pump 22 through the storage tank outflow pipe 63. The overflow pipe 62 is an example of an ozone treatment circulation pipe, and the ozone treatment water pump 21, the ozone treatment water supply pipe 61, and the overflow pipe 62 are examples of the drainage circulation mechanism 7.

  In addition, you may make it provide the ozone treatment water supply pump 21 between the waste water storage tank 2 and the ozone treatment apparatus 3, or in the ozone treatment apparatus 3 instead of in the waste water storage tank 2. FIG. Further, instead of the ozone treatment water pump 21, an ozone treatment recirculation pump (not shown) is provided in the waste water storage tank 2, between the waste water storage tank 2 and the ozone treatment apparatus 3, or in the ozone treatment apparatus 3. It may be. In this case, an ozone treatment recirculation pump is connected to the overflow pipe 62. Moreover, you may use the ozone treatment water pump 21 and the ozone treatment recirculation pump simultaneously.

  Further, the biological treatment water pump 22 may be provided outside the drainage storage tank 2. The ozone treatment water pump 21 and the biological treatment water pump 22 may be a single discharge pump. In this case, a valve is provided in each of the ozone treatment water supply pipe 61 and the storage tank outflow pipe 63. When water is sent to the ozone treatment device 3, the valve of the ozone treatment water supply pipe 61 is opened and the valve of the storage tank outflow pipe 63 is closed. When water is sent to the biological treatment tank 4, the reservoir tank outflow pipe 63 is opened and the ozone treatment water supply pipe 61 is closed. A three-way valve may be provided between one discharge pump and the ozone treatment water supply pipe 61 and the storage tank outflow pipe 63.

  As described above, the wastewater sent from the wastewater storage tank 2 is efficiently reacted with ozone by the ozone treatment device 3, and the wastewater after the ozone treatment flows back to the wastewater storage tank 2 and is sent to the ozone treatment device 3. Is repeated. In this way, by using the ozone treatment device 3 that performs ozone treatment exclusively, compared with a method of simply injecting ozone gas into the wastewater in the wastewater storage tank 2, high-molecular organic substances such as oil in the wastewater are high. Low molecular weight with efficiency.

  FIG. 3 is a schematic diagram for explaining an example of waste water treatment by the biological treatment tank 4.

  The biological treatment tank 4 has activated sludge and an air pipe 42. The air pipe 42 is connected to a blower 41 that supplies air. In the biological treatment tank 4, the wastewater in the wastewater storage tank 2 is fed through the storage tank outflow pipe 63. In addition, the waste_water | drain in the waste_water | drain storage tank 2 contains the organic substance by which the molecular weight was reduced by ozone treatment.

  The air pipe 42 has a plurality of small-diameter air outlets 43 for ejecting the air supplied from the blower 41 into the waste water containing organic matter. When air is ejected into the biological treatment tank 4 from the air outlet 43 of the air pipe 42, aerobic microorganisms contained in the activated sludge are aerated, and pollutants contained in the wastewater containing organic matter are biodegraded (oxidative decomposition). Or waste water containing organic matter is purified. Then, the waste water purified by the biological treatment tank 4 flows into the sedimentation tank 5 through the sedimentation tank inflow pipe 64. Since the air pipe 42 is disposed at the bottom of the biological treatment tank 4, the efficiency of adsorbing the aerobic microorganisms to the pollutant is obtained by stirring the waste water and activated sludge by the air ejected from the air ejection port 43. improves.

  FIG. 4 is a schematic diagram for explaining an example of waste water treatment by the settling tank 5.

  The sedimentation tank 5 includes a sediment discharge pump 51 and a sediment circulation pipe 66. In the sedimentation tank 5, the wastewater that has flowed from the biological treatment tank 4 through the sedimentation tank inflow pipe 64 is settled and separated into a precipitate and a supernatant. Next, the sediment discharge pump 51 discharges the sediment settled in the sedimentation tank 5 to the outside of the sedimentation tank 5 through the sediment circulation pipe 66 after a predetermined time has passed since the wastewater was introduced from the biological treatment tank 4. The sediment discharge pump 51 is installed at a position below a predetermined height from the bottom surface of the sedimentation tank 5 in order to discharge the sediment. Then, the supernatant liquid settled and separated is discharged from the settling tank 5 through the treated drainage discharge pipe 65 as treated wastewater to a sewage treatment facility such as an industrial park, a community plant such as an apartment house, a sewer, a river or a sea area. Is done. The sediment discharge pump 51 may be provided outside the sedimentation tank 5. Moreover, you may provide the discharge port for discharging | emitting a deposit in the position below predetermined height from the bottom face of the sedimentation tank 5, without providing the sediment discharge pump 51. FIG.

  FIG. 5 is a flowchart showing an example of wastewater treatment by the wastewater treatment system 1.

  First, wastewater discharged from a wastewater generation source such as a factory or household flows into the wastewater storage tank 2 (step S101).

  Next, the drained wastewater is stored in the drainage storage tank 2 (step S102).

  Next, it is determined whether or not the wastewater stored in the wastewater storage tank 2 is sent to the biological treatment tank 4 (step S103). For example, when a predetermined time has elapsed since the wastewater stored in the wastewater storage tank 2 is supplied to the ozone treatment device 3, it is determined that the wastewater stored in the wastewater storage tank 2 is supplied to the biological treatment tank 4. The In addition, when the organic substance amount measuring device which measures the amount of organic substances is provided in the waste water storage tank 2 and it is determined that the organic substance quantity has become a predetermined threshold value or less, the waste water stored in the waste water storage tank 2 is the biological treatment tank. 4 may be sent to water. In this case, a control device that determines whether or not the wastewater stored in the wastewater storage tank 2 is sent to the biological treatment tank 4 and controls the operations of the ozone treatment water supply pump 21 and the biological treatment water supply pump 22 is provided. It may be provided, or an administrator of the wastewater treatment system 1 may perform the determination and operation control of the pump.

  Next, when it is determined that the wastewater stored in the wastewater storage tank 2 is sent to the biological treatment tank 4 (step S103-Yes), the process proceeds to step S106. In addition, when it is determined that the wastewater stored in the wastewater storage tank 2 is not sent to the biological treatment tank 4 (Step S103-No), the wastewater stored in the wastewater storage tank 2 is sent to the ozone treatment device 3. (Step S104).

  Next, the ozone treatment device 3 mixes the waste water sent from the waste water storage tank 2 with ozone gas, and performs ozone treatment (step S105). Next, the waste water after the ozone treatment is circulated to the waste water storage tank 2, and the process is returned to step S102.

  Next, the wastewater stored in the wastewater storage tank 2 is sent to the biological treatment tank 4. (Step S106).

  Next, the biological treatment tank 4 biologically treats the wastewater sent from the wastewater storage tank 2 with activated sludge. (Step S107).

  Next, the wastewater stored in the wastewater storage tank 2 flows into the sedimentation tank 5. (Step S108).

  Next, in the sedimentation tank 5, the waste water flowing from the biological treatment tank 4 is settled and separated into a sediment and a supernatant (step S109). Then, after a predetermined time has passed since the wastewater was introduced from the biological treatment tank 4, the supernatant liquid separated and settled was treated as wastewater from the precipitation tank 5, a sewage treatment facility such as an industrial park, a community plant such as an apartment house, a sewer Then, it is discharged into a river or sea area, and the series of steps is completed.

  In addition, although it comprised so that the waste water storage tank 2 and the ozone treatment apparatus 3 might be connected via the overflow pipe 62, the ozone treatment apparatus 3 and the biological treatment tank 4 were connected via the overflow pipe (not shown). You may do it.

  As described above, the wastewater treatment system 1 of the first embodiment is configured so that the organic matter contained in the wastewater is reduced in molecular weight by the ozone treatment device 3 before biologically treating the wastewater in the biological treatment tank 4. The purification effect of the biological treatment in the treatment tank 4 can be improved.

(Second Embodiment)
FIG. 6 is a schematic diagram for explaining the outline of the waste water treatment system 10 of the second embodiment. In FIG. 6, the same components as those in the waste water treatment system 1 shown in FIG. The waste water treatment system 10 according to the second embodiment includes a measuring tank 8 and a separation device 9 in addition to the waste water storage tank 2, the ozone treatment apparatus 3, the biological treatment tank 4, and the sedimentation tank 5 shown in FIG. Prepare.

  The drainage storage tank 2 includes an ozone treatment water pump 21 and a separation device discharge pump 23. The ozone treatment water pump 21 feeds the waste water stored in the waste water storage tank 2 to the ozone treatment device 3. The separation device discharge pump 23 feeds the wastewater stored in the wastewater storage tank 2 to the separation device 9 via the measuring tank 8.

  The measuring tank 8 has a function of adjusting the flow rate of the wastewater sent from the drainage storage tank 2. By providing one or a plurality of dam plates 81 inside the measuring tank 8, the inside of the measuring tank 8 is partitioned into a plurality of rooms. In each room inside the measuring tank 8, when the water level of the drainage exceeds the height of the weir plate 81, the drainage flows into the next room, the drainage is adjusted in flow rate, and flows into the separation device 9. Instead of the measuring tank 8, an inverter-controlled flow rate adjusting pump may be provided. The flow rate adjusting pump controls the flow rate capability of the flow rate adjusting pump by controlling the rotational speed of the pump motor by inverter driving.

  The separation device 9 is a pressure levitation device, a coagulation sedimentation device, or the like, and has a function of separating suspended substances such as suspended solids and solids contained in the wastewater from the wastewater. Then, the waste water from which the suspended substances are separated by the separation device 9 flows into the biological treatment tank 4. Thus, since the wastewater treatment system 10 includes the separation device 9, the separation device 9 removes suspended solids from the wastewater, so that the purification effect of the biological treatment of wastewater in the biological treatment tank 4 at the subsequent stage is improved.

  FIG. 7 is a schematic diagram for explaining an example of waste water treatment by the separation device 9.

  A separation device 9 shown in FIG. 7 is an example of a pressure levitation device. A part of the waste water flowing in from the measuring tank 8 is pumped to a pressure tank (not shown) by a pressure pump (not shown) to generate pressurized waste water in which air is dissolved in the tank. Next, when pressurized wastewater is discharged from the pressurized wastewater discharge port 91 to the floating tank 92, ultrafine bubbles are generated by the discharge of the pressurized wastewater.

  Next, the generated ultrafine bubbles adhere to the oil and floating substances contained in the drainage and float on the upper surface of the floating tank 92. The ultrafine bubbles that have floated up, the oil, and the suspended matter are scraped off by the skimmer 93 and collected in the floss collecting unit 94. Further, the waste water from which the oil and floating substances have been separated and removed by the separation device 9 flows out into the biological treatment tank 4 through the biological treatment tank inflow pipe 95. Instead of the pressurized levitation device, oil and floating substances contained in the wastewater may be levitated by a pressurized levitation tank to separate floating substances such as suspended solids and solid matter contained in the wastewater from the wastewater.

  As described above, since the oil and floating substances are removed from the waste water by the separation device 9, the amount of the hardly decomposable polymer is reduced. Therefore, in the biological treatment tank 4 in the subsequent stage, the amount of aerobic microorganisms that can be adsorbed by the low-molecular contaminants that can be biologically processed increases, and the contaminant removal efficiency increases. Moreover, since the organic substance contained in the wastewater is reduced in molecular weight by the ozone treatment device 3, the amount of suspended matter floating in the separation device 9 is increased, and the removal efficiency of suspended matter is improved.

  Further, the oil and floating substances collected in the froth collecting section 94 are circulated to the drainage storage tank 2 through the froth circulation pipe (not shown) by a froth circulation pump (not shown) or the like, and drained again. . As a result, the amount of waste such as oil and suspended solids can be reduced, so that the amount of industrial waste processed can be reduced and the waste disposal cost can be reduced.

(Third embodiment)
FIG. 8 is a schematic diagram for explaining the outline of the wastewater treatment system 100 of the third embodiment. In FIG. 8, the same components as those in the waste water treatment system 1 shown in FIG. FIG. 9 is a flowchart illustrating an example of wastewater treatment by the wastewater treatment system 100.

  The settling tank 5 includes a sediment discharge pump 51 and a precipitate circulation pipe 66, and also includes a supernatant liquid circulation pump 52 and a supernatant liquid discharge pipe 67.

  The sediment discharge pump 51 circulates the sediment settled in the sedimentation tank 5 to the drainage storage tank 2 through the sediment circulation pipe 66 (S201), and again drains it. Thereby, it becomes possible to reduce the disposal cost of waste by reducing the amount of disposal of activated sludge and pollutants.

  The supernatant liquid recirculation pump 52 discharges the supernatant liquid in the sedimentation tank 5 to the drainage storage tank 2 through the supernatant liquid discharge pipe 67 (S202). The supernatant liquid recirculation pump 52 is installed at a position higher than a predetermined height from the bottom surface of the settling tank 5 in order to discharge the supernatant liquid. Further, an organic substance amount measuring device 53 for measuring the organic substance amount of the supernatant liquid is installed at the same height as the position where the supernatant liquid reflux pump 52 is installed. The amount of organic substances is TOC and COD.

  The supernatant liquid discharged by the supernatant liquid circulation pump 52 is stored in a storage part in the drainage branching device 54. Next, the drainage control unit of the drainage branching device 54 determines whether or not the organic matter amount of the supernatant measured by the organic matter amount measuring instrument 53 is equal to or greater than the first threshold (step S203). The drainage control unit of the drainage branching device 54 discharges the supernatant liquid to the drainage storage tank 2 through the first supernatant liquid circulation pipe 68 when the amount of the organic matter in the supernatant liquid is equal to or larger than the first threshold value (Step S203-Yes). Step S204). Moreover, the drainage control part of the drainage branching device 54 determines whether the organic matter amount of the supernatant liquid is equal to or larger than the second threshold value when the organic matter amount of the supernatant liquid is less than the first threshold value (step S203-No). Determination is made (step S205). The drainage control unit of the drainage branching device 54 discharges the supernatant liquid to the biological treatment tank 4 through the second supernatant liquid circulation pipe 69 when the amount of the organic matter in the supernatant liquid is equal to or larger than the second threshold (Step S205-Yes) ( Step S206). Note that the second threshold value is smaller than the first threshold value. The drainage control unit of the drainage branching device 54 stops the discharge by the supernatant liquid recirculation pump 52 when the organic matter amount of the supernatant measured by the organic matter amount measuring instrument 53 is less than the second threshold (No in step S205). Then, the supernatant liquid is discharged from the settling tank 5 as treated wastewater to a sewage treatment facility such as an industrial park, a community plant such as an apartment house, a sewer, a river or a sea area, and the series of steps is completed.

  Thereby, in order to control to return the waste water (supernatant liquid) to the waste water storage tank 2 when the amount of organic matter in the supernatant liquid is equal to or greater than the first threshold value, and to return to the biological treatment tank 4 when the amount is less than the first threshold value. The efficiency of wastewater treatment is improved.

  A supernatant liquid recirculation pump 52 may be provided outside the precipitation tank 5. Moreover, you may provide the discharge port for discharging | emitting a supernatant liquid in the position more than predetermined height from the bottom face of the sedimentation tank 5, without providing the supernatant liquid recirculation pump 52. FIG.

  In addition to the organic substance measuring instrument 53, a second organic substance measuring instrument 531 (not shown) is provided on the bottom surface of the sedimentation tank 5, and a second drainage branching device 541 (not shown) is provided. May be provided. In this case, the second drainage control unit of the second drainage branching device 541 is configured to remove the sediment from the first sediment circulation pipe 681 when the amount of organic matter in the sediment settled in the sedimentation tank 5 is equal to or greater than the third threshold. It discharges to the drainage storage tank 2 through (not shown). Moreover, the 2nd waste_water | drain control part of the 2nd waste_water | drain branching apparatus 541 determines whether the organic matter content of a sediment is more than a 4th threshold value, when the organic matter content of a sediment is less than a 3rd threshold value. . The second drainage control unit of the second drainage branching device 541 uses the biological treatment tank 4 to pass the sediment through the second sediment circulation pipe 691 (not shown) when the amount of organic matter in the sediment is equal to or greater than the fourth threshold. To discharge. Note that the fourth threshold value is smaller than the third threshold value. The second drainage control unit of the second drainage branching apparatus 541 stops the discharge by the sediment discharge pump 51 when the organic matter amount of the precipitate measured by the second organic matter amount measuring instrument 531 is less than the fourth threshold value. . Thereby, since the amount of deposits of sludge substances etc. can be reduced, the amount of industrial waste treated can be reduced, and the waste disposal cost can be reduced.

Result of measuring BOD (mg / L) and normal hexane extractable substance content (mg / L) of wastewater before and after ozone treatment for wastewater that flowed into ozone treatment device 3 of wastewater treatment system 1 Is shown in Table 1.

  The BOD of waste water before ozone treatment is 690 mg / L, whereas the BOL of waste water after ozone treatment is reduced to 470 mg / L. Moreover, the normal hexane extract substance content of the waste water before ozone treatment is 140 mg / L, whereas the normal hexane extract substance content of the waste water after ozone treatment is reduced to 50 mg / L.

  As described above, since the wastewater treatment systems 1, 10, and 100 can reduce the molecular weight of organic matter in the wastewater by the ozone treatment device before the wastewater flows into the biological treatment tank, the biological treatment purification effect. Can be improved. Therefore, the wastewater treatment systems 1, 10, and 100 can sufficiently remove substances that cause sludge from the wastewater.

  Note that the present invention is not limited to the first to third embodiments. For example, the wastewater treatment systems 1, 10, 100 do not include the sedimentation tank 5, but treat the wastewater purified by the biological treatment tank 4 as treated wastewater, treat sewage treatment facilities such as industrial parks, community plants such as apartment houses, It may be discharged into sewers, rivers or sea areas.

  In addition, the wastewater treatment systems 1, 10, and 100 may not include the sedimentation tank 5, and may solid-liquid separate wastewater in the biological treatment tank 4 by a membrane separation activated sludge method (Membrane Bioreactor, MBR). In the membrane separation activated sludge method, a submerged membrane separation module is provided in the biological treatment tank 4, and treated water in the membrane separation module is discharged out of the membrane separation module by a suction pump. The membrane separation module includes a membrane element for solid-liquid separation of the wastewater in the biological treatment tank 4 into treated water and activated sludge, and the membrane element is constituted by, for example, a hollow fiber membrane, a flat membrane, or a monolith membrane Is done. Thereby, the facility scale of the waste water treatment systems 1, 10, 100 is reduced, and the installation cost of the waste water treatment systems 1, 10, 100 can be reduced.

  Moreover, the activated sludge amount (Mixed liquor suspended solid, MLSS) of the wastewater in the biological treatment tank 4 may be measured, and when the MLSS is a predetermined threshold value or more, the wastewater may be recirculated to the wastewater storage tank 2. In this case, the biological treatment tank 4 removes the treated water in the membrane separation module from the wastewater treatment systems 1, 10, 100 (sewage treatment facilities such as industrial parks, community plants such as housing complexes, sewers, rivers, sea areas, etc.) In addition to the suction pump that discharges the water, a return pump for supplying the wastewater in the biological treatment tank 4 to the drainage storage tank 2 is provided. In the biological treatment tank 4, an MLSS measuring device is provided, and the waste water treatment systems 1, 10, and 100 are provided with a control device (not shown) that continuously monitors the MLSS measured by the MLSS measuring device. . When the measured MLSS is equal to or greater than a predetermined threshold, the control device controls the return pump so that the drainage is fed to the drainage storage tank 2, and when the measured MLSS is less than the predetermined threshold, the drainage is drained. The suction pump is controlled so as to be discharged out of the treatment system 1, 10, 100 (sewage treatment facilities such as industrial parks, community plants such as apartment buildings, sewers, rivers or sea areas). Thereby, when there is a lot of excess sludge in the wastewater in the biological treatment tank 4, wastewater such as excess sludge is suppressed by circulating the wastewater to the wastewater storage tank 2 and performing wastewater treatment again. It becomes possible to reduce the disposal cost. Note that the administrator of the wastewater treatment system 1, 10, 100 may monitor the MLSS measured by the MLSS measuring instrument and control the suction pump and the return pump. Further, even when a biological treatment other than the membrane separation activated sludge method is adopted, if the MLSS of the wastewater in the biological treatment tank 4 is equal to or greater than a predetermined threshold, the wastewater in the biological treatment tank 4 is recirculated to the wastewater storage tank 2. You may do it.

  Moreover, the waste water treatment systems 1, 10, 100 may be provided with two biological treatment tanks 400, 410. The biological treatment tanks 400 and 410 have the same function as the biological treatment tank 4 described above. In this case, the drainage storage tank 2 sends the wastewater to either the ozone treatment device 3 or the first biological treatment tank 400. In addition, the first biological treatment tank 400 supplies wastewater to the ozone treatment apparatus 3, and the ozone treatment apparatus 3 circulates the wastewater to either the wastewater storage tank 2 or the first biological treatment tank 400. . Furthermore, the first biological treatment tank 400 supplies the wastewater to the second biological treatment tank 410, and the second biological treatment tank 410 sends the wastewater to the precipitation tank 5. In addition, between the organic substance amount measuring device which measures the amount of organic substances in the first biological treatment tank 400, and the biological treatment tank for feeding the waste water in the first biological treatment tank 400 to the second biological treatment tank 410. A pump may be provided, and when it is determined that the amount of organic substances has become a predetermined threshold value or less, the wastewater stored in the first biological treatment tank 400 may be sent to the second biological treatment tank 410. In this case, a controller is provided that determines whether or not the wastewater stored in the first biological treatment tank 400 is sent to the second biological treatment tank 410 and controls the operation of the inter-biological treatment tank pump. Alternatively, an administrator of the wastewater treatment system 1, 10, 100 may perform the determination and control of the operation of the biological treatment tank pump. Further, two or more second biological treatment tanks 410 may be provided in series. For example, when two second biological treatment tanks 410 are provided, the wastewater stored in the first biological treatment tank 400 is sent to the first tank of the second biological treatment tank 410, The wastewater stored in the first tank of the second biological treatment tank 410 is sent to the second tank of the second biological treatment tank 410 and stored in the second tank of the second biological treatment tank 410. The discharged waste water is sent to the settling tank 5.

  It should be understood by those skilled in the art that various changes, substitutions, and modifications can be made thereto without departing from the spirit and scope of the present invention.

1, 10, 100 Wastewater treatment system 2 Wastewater storage tank 21 Ozone treatment water pump 22 Biological treatment water pump 23 Separation device discharge pump 3 Ozone treatment device 31 Cylindrical container 32 Ozone ejection nozzle 33 Ozone ejection port 4 Biological treatment tank 41 Blower 42 Air piping 43 Air outlet 5 Sedimentation tank 51 Sediment discharge pump 52 Supernatant liquid recirculation pump 53 Organic matter measuring instrument 54 Drainage branch device 60 Reservoir inflow pipe 61 Ozone treatment water supply pipe 62 Overflow pipe 63 Reservoir outflow pipe 64 Precipitation tank inflow Pipe 65 Treated drainage discharge pipe 66 Precipitate reflux pipe 67 Supernatant liquid discharge pipe 68 First supernatant liquid reflux pipe 69 Second supernatant liquid reflux pipe 7 Drainage circulation mechanism 8 Measuring tank 81 Weir plate 9 Separating device 91 Pressurized drainage outlet 92 Floating tank 93 Skimmer 94 Floss collecting part 95 Biological treatment tank inflow pipe

Claims (8)

A wastewater storage tank for storing wastewater containing organic matter;
An ozone treatment device that lowers the molecular weight of organic matter contained in the wastewater by ozone treatment of the wastewater;
A drainage recirculation mechanism that feeds the wastewater stored in the wastewater storage tank to the ozone treatment device and recirculates the ozone treated wastewater to the wastewater storage tank;
A biological treatment tank that contains the ozone-treated wastewater and that is brought into contact with aerobic microorganisms to the wastewater sent from the wastewater storage tank to reduce organic matter contained in the wastewater,
The ozone treatment apparatus has a cylindrical container having a nozzle for ejecting ozone gas,
The drainage recirculation mechanism is
An ozone treatment water pipe provided between the waste water storage tank and the ozone treatment device, for feeding the waste water stored in the waste water storage tank to the ozone treatment device;
An ozone treatment recirculation pipe provided between the waste water storage tank and the ozone treatment device, for recirculating the ozone treated waste water to the waste water storage tank;
An ozone treatment water pump that feeds the wastewater stored in the wastewater storage tank to the ozone treatment device,
The nozzle is disposed so as to protrude upward from a substantially central portion of the bottom surface of the cylindrical container,
The lower end of the connection port of the cylindrical container of the ozone treatment reflux pipe is located at a predetermined height from the nozzle outlet,
The ratio of the predetermined height to the inner diameter of the bottom surface of the cylindrical container is in the range of 0.3 to 1.0.
A wastewater treatment system characterized by that.   The biological treatment tank is provided between the wastewater storage tank and the biological treatment tank, and separates the suspended matter or solid matter contained in the wastewater, and the wastewater from which the suspended matter or solid matter is separated from the wastewater storage tank. The wastewater treatment system according to claim 1, further comprising a separation device that feeds water into the waste water.   The wastewater treatment system according to claim 2, further comprising a floss circulation pipe for circulating the suspended matter separated in the separation device to the wastewater storage tank.   The wastewater treatment system according to claim 2 or 3, wherein the separation device is a pressurized flotation device or a coagulation sedimentation device.   The ozone treatment apparatus according to any one of claims 1 to 4, wherein the ozone treatment apparatus is a swirling jet type ozone treatment apparatus that stirs ozone gas and drainage by generating a swirling phenomenon of a jet flow by ozone gas ejected from the nozzle. The described wastewater treatment system. The drainage tank is
A measuring instrument for measuring the amount of organic matter in the wastewater stored in the wastewater storage tank;
When the amount of organic matter in the wastewater stored in the wastewater storage tank is greater than or equal to a predetermined threshold, the wastewater stored in the wastewater storage tank is sent to the ozone treatment device, and the amount of organic matter in the wastewater is less than the predetermined threshold In this case, the wastewater treatment system according to any one of claims 1 to 5, further comprising a control device that feeds the wastewater stored in the wastewater storage tank to the biological treatment tank. It further comprises a sedimentation tank that separates the waste water into sediment and supernatant,
The wastewater treatment system according to any one of claims 1 to 6, wherein the sedimentation tank includes a sediment discharge pump that circulates the sediment settled in the sedimentation tank to the wastewater storage tank. Storing wastewater containing organic matter in a wastewater storage tank;
A step of causing the drainage recirculation mechanism to feed the wastewater stored in the drainage storage tank to an ozone treatment apparatus having a cylindrical container having a nozzle for ejecting ozone gas;
The ozone treatment device ozone-treats the sent wastewater to lower the organic matter contained in the wastewater;
The drainage recirculation mechanism circulating the ozone-treated wastewater to the drainage storage tank;
A biological treatment tank containing the ozone-treated wastewater and contacting wastewater sent from the wastewater storage tank with aerobic microorganisms to reduce organic matter contained in the wastewater;
The drainage recirculation mechanism is
An ozone treatment water pipe provided between the waste water storage tank and the ozone treatment device, for feeding the waste water stored in the waste water storage tank to the ozone treatment device;
An ozone treatment recirculation pipe provided between the waste water storage tank and the ozone treatment device, for recirculating the ozone treated waste water to the waste water storage tank;
An ozone treatment water pump that feeds the wastewater stored in the wastewater storage tank to the ozone treatment device,
The nozzle is disposed so as to protrude upward from a substantially central portion of the bottom surface of the cylindrical container,
The lower end of the connection port of the cylindrical container of the ozone treatment reflux pipe is located at a predetermined height from the nozzle outlet,
The ratio of the predetermined height to the inner diameter of the bottom surface of the cylindrical container is in the range of 0.3 to 1.0.
A wastewater treatment method characterized by that.